A Dynamic Equivalence Method of DFIG Based on Similarity Coherence

Abstract

The invention discloses a doubly-fed wind motor dynamic equivalence method based on similarity homology. The method comprises the following steps of stepS10, using a prony algorithm to fit the outputpower of doubly-fed wind motors to the linear combination of the exponential functions of an amplitude, a phase, a frequency and damping; stepS20, according to the linear combination acquired from thestepS10, using a similarity theory to determine a similar oscillation mode between the doubly-fed wind motors; stepS30, using the similar oscillation mode to define a homology similarity quantification index between the doubly-fed wind motors, and discriminating a homology cluster in a wind power plant; S40, taking active power output by the doubly-fed wind motors as weight and acquiring the equivalent transient internal potential of an equivalent machine, and connecting the equivalent transient internal potential buses of the doubly-fed wind motors of a same group to the equivalent transient internal potential bus of the equivalent machine through a complex transformation ratio phase shifting transformer respectively; and stepS50, calculating the equivalent parameter of each equivalentmachine, and connecting the equivalent transient internal potential bus of the equivalent machine to the equivalent machine through an equivalent doubly-fed wind motor impedance.

Description

technical field [0001] The invention relates to the technical field of equivalent modeling of wind farms in new energy power generation technology, in particular to a dynamic equivalent method for double-fed wind generators based on similarity coherence. Background technique [0002] With the rapid development of the modern power industry, large-scale AC and DC interconnected power systems have emerged, and the characteristics of multi-machines (thousands of machines) and large power grids (thousands of lines and thousands of busbars) have become more and more prominent, which makes the power system The calculation of planning, design and operation mode has become extremely cumbersome and complicated. On the one hand, it takes a lot of time and space to complete these calculations in detail. On the other hand, due to the limitation of simulation scale and hardware equipment, the above calculations are difficult to realize in practice. To this end, some reasonable simplifica...

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Problems solved by technology

At present, there are few relevant literatures on how to distinguish the coherent characteristics of wind farms. The relevant literatures propose a method of coherent grouping according to the characteristic quantity, but this kind of method has the problem of whether the selection of the characteristic quantity is complete, and the universality of this method is an obstacle. The bottleneck of its application

The similarity grouping based on disturbed trajectories is a common method for multi-machine system grouping, and the power angle of the generator is often used as the observation value. Unlike the synchronous motor, due to the existence of power electronic equipment in the doubly-fed fan, the Its external dynamic characteristics are quite different from those of traditional synchronous generators. Therefore, when performing coherence discrimination on wind turbines, there is no consensus on which variable disturbed trajectories to use for comparison.

In addition, since the doubly-fed wind turbine adopts decoupling control, it does not reflect the inertia externally, and its impact on the system is only characterized by the amount of output power. At present, there are few relevant literatures on the method of wind turbine parameter aggregation.

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